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From |
"Nailing Xia" <nailingxia@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Multiple imputation showing missing values during imputation |

Date |
Thu, 11 Dec 2008 20:46:41 -0500 |

Hi, I've done some experiment with the -interval- option in -ice- command. And I found that the missing imputed value problem (i.e., Stata indicating values for several cases of the variables imputed using -intreg- are missing from previous cycle, see below email for more information) goes away when I only include one interval variabel in the interval option. The problem only occurs when there are 2 or more variables included in the -interval- option. So I suspect that it could be the syntax I wrote for the interval option is not correct. I read the help menu for -ice-, but couldn't figure out what is wrong with the syntax. So I am posting my code here--if you know the right syntax, please help! My code looks like (here I ommited some variables as well as options including substitute, cmd, passive, saving, and weights): ice age1 llage1 ulage1 age2 age3 llage3 ulage3 age4 age5 redlun4 llredlun4 ulredlun5 redlun5 llredlun5 ulredlun5.....interval(age1: llage1 ulage1, age3: llage3 ulage3, redlun4: llredlun4 ulredlun5, redlun5: llredlun5 ulredlun5) Any thought or suggestions are very much appreciated! Thanks, Nailing Xia On Tue, Dec 9, 2008 at 5:42 PM, Michael I. Lichter <mlichter@buffalo.edu> wrote: > Nailing, > > Does -ice- provide information on each individual estimation? If so, you > should check the -intreg- runs -- it may be that -intreg- is failing for > some reason, possibly related to your interval() specifications, and that > this is where the missing imputation data is coming from. > > Michael > > Nailing Xia wrote: >> >> Thanks, Michael. I checked the lower bound and upper bound variables >> as well as the interval variables for cases that Stata report imputed >> values being missing, but didn't find anything that looks strange. As >> a matter of fact, those cases are within an interval (i.e., both the >> lower bound and upper bound variables have a valid but different >> value, indicating that the interval variable should be imputed within >> that range) that needs an imputation with -intreg-. >> >> And here're the details of the dataset: I am using a longitudinal >> dataset that follows over 10,000 children for several years. The >> dataset has 5 waves, and in the model I included over 8,000 >> individuals. The -ice- command includes around 50 variables in >> total--as some of the variables are time-specific but some are not, >> the total number of variables are around 200. Options I used with >> -ice- include "sub", "passive", "cmd", and "interval". For all imputed >> variables (including categorical variables), I use -regress- (except >> for those that are included in the "interval" option and thus use >> -intreg-"). In "interval" option, I included 21 variables (out of over >> 200 variables included in -ice-), and 15 of them have the imputed >> value missing problem as described earlier. The number of missing >> cases range from 1 to 49. What happens is that Stata will replace the >> missing cases with mean and continue imputing. Then at cycle 6 when it >> is imputing one of the variable that has the imputed value missing >> problem, Stata shows that "convergence not achieved" and stops >> imputing (although I am not sure whether this problem relates to the >> imputed value missing problem). >> >> If you know anything about this problem, please help. Thanks a lot! >> >> Nailing Xia >> >> >> On Tue, Dec 9, 2008 at 3:23 PM, Michael I. Lichter <mlichter@buffalo.edu> >> wrote: >> >>> >>> Nailing, >>> >>> I suspect that you haven't gotten any responses because your question is >>> (or >>> appears to be) very specific to your data, but you don't say much about >>> the >>> specifics of your data. It might be helpful to describe the variables >>> involved and the constraints you are putting on the imputed data using >>> the >>> -interval- option to -ice-. >>> >>> Here's a stab in the dark, though. Is it possible that one or more of >>> your >>> interval variables are missing for two cases in which your variable >>> redlun5 >>> is missing as well? If not, can you at least identify the two cases for >>> which -ice- is failing to make an imputation and see if there is anything >>> unusual about those cases' values on the other variables in the >>> imputation? >>> >>> -ml >>> >>> Nailing Xia wrote: >>> >>>> >>>> Hi, >>>> >>>> I am using -ice- for multiple imputation, and during the imputation >>>> process, Stata shows that values for several imputed variables that >>>> should have been imputed in previous cycle are actually missing. The >>>> actual error message reads as: "I found that 2 missing value(s) of >>>> redlun5 that should have been >>>> imputed were missing at cycle 2. Replacing value(s) with mean, dumping >>>> current data to file _ice_dump.dta and continuing." >>>> >>>> Anyone knows what seems to cause this problem? By the way, this >>>> problem did not exist when I imputed without using the -interval- >>>> option. But I checked my code for -interval- option, and it seems >>>> fine. >>>> >>>> Many thanks! >>>> Nailing Xia >>>> * >>>> * For searches and help try: >>>> * http://www.stata.com/help.cgi?search >>>> * http://www.stata.com/support/statalist/faq >>>> * http://www.ats.ucla.edu/stat/stata/ >>>> >>>> >>> >>> -- >>> Michael I. Lichter, Ph.D. >>> Research Assistant Professor & NRSA Fellow >>> UB Department of Family Medicine / Primary Care Research Institute >>> UB Clinical Center, 462 Grider Street, Buffalo, NY 14215 >>> Office: CC 125 / Phone: 716-898-4751 / E-Mail: mlichter@buffalo.edu >>> >>> * >>> * For searches and help try: >>> * http://www.stata.com/help.cgi?search >>> * http://www.stata.com/support/statalist/faq >>> * http://www.ats.ucla.edu/stat/stata/ >>> >>> > > -- > Michael I. Lichter, Ph.D. > Research Assistant Professor & NRSA Fellow > UB Department of Family Medicine / Primary Care Research Institute > UB Clinical Center, 462 Grider Street, Buffalo, NY 14215 > Office: CC 125 / Phone: 716-898-4751 / E-Mail: mlichter@buffalo.edu > > * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**st: Multiple imputation showing missing values during imputation***From:*"Nailing Xia" <nailingxia@gmail.com>

**Re: st: Multiple imputation showing missing values during imputation***From:*"Michael I. Lichter" <mlichter@buffalo.edu>

**Re: st: Multiple imputation showing missing values during imputation***From:*"Nailing Xia" <nailingxia@gmail.com>

**Re: st: Multiple imputation showing missing values during imputation***From:*"Michael I. Lichter" <mlichter@buffalo.edu>

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